Detonator and composition for the same



Patented Sept. 26, 1933 I UNITED STATES- PATENT OFFICE DETONATOR AND COMPOSITION ron THE SAME

No Drawing. Application December 15, 1930 Serial No. 502,559

15 Claims.

This invention relates to improvements in blasting caps which are used for initiating charges of explosives.

Its object is to provide blasting caps of the 5 compound or booster type which are marked by great economy and by decreased hazard in manufacture and use, but with no sacrifice'of efiiciency. A further object is the adaptation of an improved type of primary detonating substance as the initiator for the base charge in compound blasting caps. The invention is applicable to either electric or safety fuse types of blasting caps.

Compound blasting caps comprise a base charge of some explosive which is not usually a primary detonating substance in itself. Examples of base charges are tetryl, trinitrotoluene, nitrocellulose; in fact, solid explosives generally are possibilities. The primary detonating or initiating substance for the base charge has, in practice, usually been mercury fulminate or an azide. Confining capsules may be positioned in various parts of the loading, as between the initiator and base charge or above the initiator.

The previously used primary detonating substances have been characterized by extreme sensitiveness to impact, friction and handling generally. They are also hazardous in manufacture and quite costly.

I have now found a type of primary detonating substance for compound blasting caps which approaches the ideal. Solid organic nitrates of the general formula CnHn+2(NO3)n, of which hexanitromannite is an example, have received consideration as admixtures in dynamites, blast- 35 ing cap compounds, primers and certain military compositions. A well known type of blasting cap may consist of a mixture of mercury fulminate, nitrocellulose, potassium chlorate and hexanitromannite. It has been proposed that a blasting cap be made by pressing a compound of the proposed type in a shell and igniting it with a hot flame composition such as amixture of barium nitrate, magnesium powder and lead hypophosphite.

World-wide tendency has been toward compound blasting caps because of their greater economy, decreased hazard and great efliciency. As a base charge an explosive may be used which is stronger, cheaper, safer and more effective 50 than most primary detonating substances. Most any solid explosive such as tetryLTNT, nitrocellulose, nitrostarch, hexanitromannite, tetranitroerythrite, trinitrobenzene, etc., maybe used in this relation. It will be observed that these 55 cited base charges are less sensitive to friction and impact than mercury fulminate, lead azide and diazodinitrophenol. Tendencies in the use of primary detonating substances for such blasting caps have been toward those of which the lesser amounts are necessary, because of the resultant economy and the decreased amounts of hazardous materials that it is necessary to handle. Thus azides and diazodinitrophenol are replacing mercury fulminate for the above reasons. However, such compounds are all highly haza'rdous in handling with respect to impact, friction and pressure. The use of decreased quantities involves only a partial elimination of hazard, at the best, while in some of the manufacturing operations it is of no value and results in no hazard elimination whatever, for the user.

I have searched repeatedly, and over an extended period, for a primary detonating substance which would be suitable for initiating the base charge in compound blasting caps and would be less hazardous than known compounds for the purpose. In the discovery of the adaptability of compounds of the proposed type, namely organic nitrates of the general formula CnHn+2(NO3)n, I have been successful beyond expectation. In addition to achieving the stated aims, I have also obtained a higher degree of initiating efliciency than is offered by mercury fulminate and a higher strength than is offered by other known primary detonating substances.

In my examples I will refer to tetryl as the base charge and hexanitromannite as the primary detonating substance. This is in no respect limiting since I may use base charges that are suitable with other primary detonating substances and I may use primary detonating substances of the general formula CnHn+2(NO3)n.

In the following table the base charge was always 0.30 gram tetryl pressed at and an 95 inner capsule was used over the hexanitromannite.

The above indicates that under an inner capsule as little as.0.15 gram hexanitromannite will detonate a tetryl base charge, whether the pressure is 50 lbs. or 200 lbs.

Some Bureau of Mines type sand tests results were: i

| Weight of Tet 1 Weight of Hexanitro- Grams oi tetryl base gg at hexanitromannite sand charge p mannite pressed at crushed Gram Pounds Gram Pounds It is here indicated that a base charge of 0.15 gram tetryl and a primer charge of 0.25 gram of hexanitromannite is, suitable for a No. 6 blasting cap and that a base charge of 0.60 gram tetryl and a primer charge of 0.25 gram hexanitromannite is suitable for a No. 8 blasting cap.

In testing primary detonating substances for frictional sensitiveness one of my tests upon which I place much reliance consisted in placing a small amount of sand in a copper cup, loading the substance on it and pressing with a revolving steel press point, with facilities to record the pressure when detonnation occurred. The results in a series of tests were:

Average 12585}!- sure a w 0 Primary detoneting substances dtonafion occurred Pounds Mercury fnlminaio 264 80-20 mercury iulrninate-potassium chlorate 320 Diazodinitrophenol 340 75-25 diazodinitrophenol-potassium chlorate. 240 Lead Mirin 181 Mercurious azide 215 Hexanitromannite No explosigiggo Another test upon which I place much reliance consisted in placing a small amount of the substance on a hardened steel anvil, inclined at a'20 angle and dropping a steel ball weighing approximately 80 grams on the substance; noting the height of fall necessary to cause complete detonation.

Results in a series of tests were:

In this test of hexanitromannite which was made at the maximum height possible with the apparatus, it was noted that some very slight local -.crackings occurred at the point of contact between the steel ball and the steel anvil. In no case did these slight crackings propagate to the balance of the substance, which is a very desirable feature and of great importance inomanufacturing blasting caps. It is indicated in these tests that hexanitromannite presents the least hazard by a wide margin. An important feature of my present invention resides in the provision of suitable and adequate igniting means for the primary charge. The present application is intended to cover broadly 7 the use of substances having the general formula CnHn+2(No3)n as the primary charge in compound detonators, irrespective of the par-- ticular igniting means which may be employed. However, it is highly important to employ a suitablev and effective ignition means, because, since the material of the primary charge is less sensitive than mercury fulminate and other commonly employed initiators, such insensitiveness must be compensated for by the use of particularly reliable and effective igniting means or flash composition. While I do not desire to limit this application to the use of any particular igniting medium, yet, in order to recite a completely operative combination, I may refer to the disclosure of my co-pending application Serial No. 502,560, filed December 15, 1930, the match heads there described having been found by me to be satisfactory igniting mediums for detonators of the character contemplated in this application. The synthetic manufacture of mannite has been developed to a point where it is much cheaper than the same product from natural sources. Accordingly, in consideration of this, together with the fact that such small quantities of nitromannite are requisite for the primary charges thereof, my novel type of compound detonator is believed more economical than any heretofore known or used.

It is to be understood that the solid explosive substances of the general formula CnHn+2(No3) n, specified as essential to my invention, may be the ordinary grades of impure products usually produced, for example by the nitration of the commercial forms of the required polyhydric alcohols of the general formula CnHn+2(0I-I)n; the said nitration products being prone to contain certain impure isomers, lower nitric esters, etc. They may, however, also be the chemically pure compounds, as obtained, for example, by recrystallization of impure forms, from a suitable solvent or solvents. Hexanitromannite, or nitromannite, for example, may refer either to the chemically pure hexanitric ester or it may include proportions of the lower nitric esters, mixed therewith.

Having described my invention, which I claim 1. A compound detonator in which the primary detonating substance is a solid explosive of the general formula CnHn+2(NO3)n.

2. A compound detonator in which the primary detonating substance is a mixture of solid organic nitrates of the general formula CnHn+2(NO3) n.

3. A compound detonator in which the base charge is an explosive which is not a primary detonating substance and upon which is placed 3 a primary charge of a solid composition of the general formula CnHn+(NOa) n.

4.'A compound detonator in which the base charge is a solid explosive which is less sensitive to friction and impact than mercury fulminate, lead azide and diazodinitrophenol and upon which is placed a primary charge of a solid nitration product of the general formula CnHn+2 (N03) n- 5'. A compound detonator whose primary charge consists of a solid nitration product of the general formula CnHn+ (NOa)n and a stabilizing agent.

6. A compound detonator consisting of a base charge of tetryl and a primary detonating charge of. hexanitromannite.

'7. A compound detonator comprising a base charge of tetryl anda primary charge consisting of hexanitromannite.

8. A compound detonator comprising a base' ecaaoa charge and a primary charge having as an essential ingredient hexanitromannite.

9. As a new article of manufacture, a detonator including, in combination, a shell, a base charge of a solid explosive which is less sensitive to friction and impact than mercury fulminate, lead azlde and diazodinitrophenol, a primary charge consisting of a mixture of a solid explosive substance of the general formula CnHn+2(No3)n and a stabilizing agent, a. perforated inner capsule pressed over the said primary charge, and an ignition medium for the said-charge.

10. A detonator comprising, in combination, a shell, a base charge of an explosive which is not a primary detonating substance, a primary detonating charge of a solid organic nitrate of the general formula CnHn+2(NO3)n, a perforated inner capsule pressed over the said primary charge, and a suitable ignition medium for the said charge.

' 11. A detonator comprising, in combination, a shell, a base charge of an explosive which is less sensitive than mercury fulminate, lead azide and diazodinitrophenol, ap rimary detonating charge of a mixture of a solid organic nitrate of the general formula CnHn+2(NO3)n and a stabilizing agent, a perforated inner capsule pressed over the said primarycharge, and a suitable igniting medium for the said charge.

12. A compound detonator including a base charge of tetryl and upon which is placed a primary charge consisting of hexanitromannite and a stabilizing agent.

13. A detonator as recited in claim 9 characterized by having hexanitromannite as the solid ex-' plosive constituent of the said primary charge.

14. A detonator as recited in claim 9 characterized by having tetryl as the said base charge thereof.

15. A detonator comprising a shell, a base charge of a solid explosive less sensitive to friction and impact than mercury fulminate, lead 'azide and diazodinitrophenol, a superimposed primary charge of a solid nitration product of the general formula CnHn+2(NO3)n, and a hot flash material of such composition as to quickly ignite and bring about detonation of the primary charge of CnHn+2(NO3) n.

SYLVESTER B. LARGE.

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